The present invention relates generally to an internal combustion engine, and particularly to an internal combustion engine that utilizes fuel injection and cross scavenging.
Internal combustion engines generally have one or more cylinders through which one or more pistons move in a reciprocating manner. Each piston is connected to a crankshaft by a connecting rod able to deliver force from the piston to the crankshaft to rotate the crankshaft. Power to drive the piston is provided by igniting a fuel-air mixture disposed in the cylinder on a side of the piston opposite the connecting rod. The fuel-air mixture is ignited by some type of ignition device, such as a spark plug.
Some internal combustion engines, such as cylinder ported, two-stroke engines, utilize a scavenging process to promote mixing of the air and fuel. One type of scavenging process is referred to as loop scavenging. A loop scavenged engine includes two or more scavenge ports in each cylinder that are directed toward the side of the cylinder away from the exhaust port. Generally, the inflow of air or air-fuel mixture is across a piston having an essentially flat top.
Another type of scavenging is referred to as cross scavenging. A cross scavenged engine or cylinder utilizes a deflector to deflect the mixture of air and fuel intaken through the scavenge or intake ports of each cylinder. Often, the deflector is formed on the crown of the piston in the form of a wall or barrier. This type of design utilizes scavenge ports and exhaust ports that are disposed on directly opposite sides of the cylinder, permitting the direct drilling of the scavenge and exhaust ports. This allows for a less expensive manufacturing process and permits closer cylinder-to-cylinder spacing. Additionally, at least some cross scavenged engines have relatively good fuel efficiencies and low emissions at low speed and/or part throttle.
It would be advantageous to gain the benefits of a cross scavenged engine design with improved control over combustion to promote starting, fuel economy and power of the engine throughout the range of engine speeds.
The present invention features a cross scavenged engine that can be used to power, for example, a watercraft. In one embodiment, the engine is utilized with an outboard motor which can be used to move a vehicle along a body of water. The performance of the engine is improved by utilizing a fuel injection system for injecting a fuel into the one or more cylinders of the engine. The injection of fuel improves the operating characteristics of a cross scavenged by cooling the piston during vaporization of the injected fuel. This vaporization, in turn, allows for a better burn or combustion in the one or more cylinders.